[1] Univ Antwerp Hosp, Dept Anesthesiol, B-2650 Edegem, Belgium
[2] Univ Roma Tor Vergata, European Hosp, Dept Anesthesia & Intens Care, Rome, Italy
[3] Sudbury Reg Hosp, Dept Anesthesia & Crit Care, Sudbury, ON, Canada
[4] Marquette Univ, Med Coll Wisconsin, Dept Biomed Engn, Dept Anesthesiol, Milwaukee, WI 53233 USA
[5] Marquette Univ, Med Coll Wisconsin, Dept Biomed Engn, Dept Physiol, Milwaukee, WI 53233 USA
[6] Vet Affairs Med Ctr, Res Serv, Milwaukee, WI USA